COVID-19 has revealed that our human health relies on environmental health. In Marin County, we now have an opportunity to come into alignment with the natural world by using plants to improve the impaired water quality in the Civic Center lagoon. The horrific fish die-off on August 10, 2020, revealed beyond doubt that the waters in the Marin Lagoon need our help!
We are taking an eco-systemic approach. The Gallinas Watershed Council (GWC), with Supervisor Damon Connolly and three students from the Environmental Forum, installed the “floating islands” demonstration in the lagoon during the 2015 Bioneers Conference. The CCWR (Civic Center Watershed Restoration) pilot project has successfully shown how nature itself can improve water quality when allowed to flourish.
The GWC has worked with Marin County Staff, agencies with jurisdiction over the lagoon, local advocates, indigenous cultural practitioners, Traditional Ecological Knowledge (TEK) experts, and neighborhood groups. All the constituents agree that floating ecosystems at scale, with an appropriate selection of native hydrophytes, can provide the biological filtration needed to regenerate the health, well-being, and beauty of the Marin Lagoon and Lagoon Park.
Suspended native plants utilize nutrients directly from the water column. Plant roots exude bacteria and enzymes that jumpstart the ecosystem by feeding the base of the food chain. Increased nutrient cycling has helped decrease siltation in stagnant benthic layers and consequently, the need for dredging. In the Marin Civic Center Lagoon, the super-accumulators or plants that could really drive the system are Willows and Tule.
How do bio-filters work?
Floating islands cool waters by providing shade and refuge. Native plants, Marin County sourced, sequester carbon and help regenerate both terrestrial and aquatic ecosystems. Plant roots support a robust and complex microbial environment, acting as an incubator for beneficial micro-organisms; arthropods, nematodes, invertebrates, and so on up the food chain. Plants grow by utilizing nutrients in the water while sustaining the healthy functioning of living things.
1-3% of the surface of the Lagoon needs to be covered with floating ecosystems. The increase in habitat for local and migratory wildlife will sustain the lagoon’s beauty and systemic health.
Benefits of bio-filters
- Reduction and removal of nitrates, phosphates, heavy metals, and organic waste.
- Movement of nutrients up the food chain, rather than feeding large blooms of algae.
- Oxygenation: plant roots and living creatures transport oxygen down into the water column.
- A healthier body of water and a thriving ecosystem, including bigger fish.
A living edge would be the best ecological solution for the lagoon and reflects Wright’s original design intention. Bioswales could promote infiltration before waste from lawns and pathways contact the water. Floating ecosystems can provide the needed filtration (at 1% to 3% of the surface area of the lagoon) and would not require removal nor addition of concrete.